Thermostatic damper mechanism



Patented ct, 7, 1941 UNITED STATES PATENT OFFICE 2,258,506 THERMOSTATIC DAMPER MECHANISM I l Michael Fisher, Providence, R. I. Application May 20, 1940, Serial No. 336,103

3 Claims.

Damper controls as usually positioned in the smoke-stacks of boilers, and particularly boilers for domestic use, are adapted to be manually turned, or to be mechanically moved by` pressure or temperature control means. These controls are disadvantageous in that they do not depend directly on the temperature of the hot uegases, and do not function as safety valves in the -event of explosions in the boiler and in the ues resulting from ignition of incompletely combusted gases.

It is the principal object of my invention to provide a damper control which opens automatically in response to an increase in temperature of the flue gases, this novel control being further provided with'simple means for regulating the extent of movement, and being arranged so Aas to immediately assume a closed position in the event of an explosion -or other accumulation of pressure gases in the boiler and the boiler flues.

Another object of my invention is to provide a supplementary damper control for a manually adjustable mechanism for ypermitting a regulated flow of air into the smoke stack to control the total draft. y

With the above and other objects and advantageous features inA mind, my invention con' sists of a novel arrangement of parts more fully disclosed in the detailed description following, in conjunction with the accompanying drawing, and more specifically defined in the claims appended thereto.

Fig. 1 is a perspective view of the novel damper, the arrangement being for horizontal mounting 4on a smoke-stack pipe;

Fig. 2 is a side view, partly in section;

Fig. 3 is a vertical transverse section thereof; and

Fig. 4 is a side view of the novel damper as it appears when mounted vertically.

Referring to the drawing, the boiler may be of any standard type and equipped with the usual smoke flue; the novel damper assembly IIJ is mounted therein, the preferred mounting being Vina horizontal positionya vertical position may be used if desired, but the horizontal mounting is more suitable for the average installation.

The novel damper assembly I includes abase II of generally arcuate rectangular form with a plurality of openings vI2 for riveting to a smokestack pipe, the base having an upstanding cage I3 provided with a central opening I4, the side and top edges of the cage being cast to provide flanges I5 around the opening I4 to serve as damper is provided with two pivot rods I1, I8 at its upper edges, the pivot rod I8 being elongated for a purpose hereinafter described, the pivot rods extending outwardly through arcuate openings I9 in the cage sides.

Referring now to Fig. 2, a thermostatic coil 20 has its inner end 2| locked to a removable support bracket 22 secured to the rear of the cage, the thermostatic coil having its other end formed as a spring finger 23 which extends upwardly and terminates in an arcuate tip 24 adapted to slidingly contact the rear of the damper I6. A stop element 25, see Fig. 3, includes a hub portion 26 mounted on the pivot bar I8 and adapted to be locked there in selected position in any desired manner, as by a set screw 21, the hub having a nger 28 extending therefrom, the nger being bent so as to contact a fixed stop 29 on the damper assembly, whereby the novel stop element may be set in desired position, and will turn with downward movement ofthe damper until the finger 28 contacts the stop 29 to lock the damper against further downward movement.

Referring now to Figs. 3 and 2, it will be noted that the damper is pivotally mounted on the rods I1 and I8, and that itsl centre of gravity falls outside the pivot point, movement of the thermostatic coil 25 upon increase in temperature of the flue gases traversingthe stack will permit a movement of the damper I6under the iniiuence of gravity, and thus open the damper to allow entrance of air into the flues. `In the event of an accumulation of gases under pressure in the boiler and flues, or of an explosion in the boiler and ues, the increased pressure functions to move the damper I6 upwardly into a closed position, as there is no locking of the damper end due to mechanical connection with the thermostatic element.

The above described thermostatic damper control is entirely automatic in operation. For many installations, it is desirable to also use an auxiliary draft control, the preferred construction embodying all the mechanism in one unit.

Thus, a housing' 30 is detachably secured to 34 being pivotally mounted in the sides so as to be normally retained in closed lposition by their own weight, each having a threaded bolt 35 extending outwardly therefrom equipped With manually adjustable threaded disk weights 36, whereby the dampers may be adjustably set so as to swing open to a desired extent to control the actual volume of air passing through the thermostatically controlled damper I6.

As shown in Fig. 3, the dampers 34 may be set vertically, the

' housing having a plurality of pivot eyes 37 and the dampers having removable pivot pins 38 for this purpose.

The offset arrangement of the cage so as to `permit gravity movement of the damper I6 whether the control is mounted horizontally or vertically, and the interchangeable mounting of the side dampers 34 to correspond, facilitate the installation to accommodate any type of smoke stack. In large units for heavy duty, two or more thermostatic coils may be used, and if desired, the housing 30 may lbe replaced by two smaller damper housings inserted in the smoke stack direct, or the flanges Il may be extended sufficiently to form supports for the dampers, thus affording parallel instead of series flow of air to the smoke-stack through the side dampers and the thermostatic damper.

The parts are simply constructed, are readily curedto the casing and depending therefrom to be positioned in the smoke stack, the other end of the coil being free and contiguous said air inlet opening, and a damper freely pivotally mounted in said cage to extend across said opening and adapted to swing downwardly under the influence of gravity' to open said opening, said damper resting on and being slidably engaged by said free end of the coil, said cage having side andv end walls, one end wall being of substantially less height than the other end wall and the 4side walls sloping correspondingly to permit opening downward movement of the damper -by gravity when the casing is set in either horizontal or vertical position. f

2. In a damper arrangement for a smoke stack, a casing having a base and a cage upstanding therefrom, the top of said cage having an air inlet opening, a thermostatically actuated damper pivotally mounted in said cage overlying said air inlet opening and for controlling passage of air through said opening, a housing on said cage having an upper wall, side and end walls, air inlets in said side walls, and adjustable draft operated. auxiliary dampers for said air inlets pivotally mounted in said side walls. l

3. In a damper arrangement for a smoke stack, a casing having a base and a cage upstanding therefrom, the top of said cage having an air inlet opening, a damper freely pivotally mounted in said cage for controlling passage of air through said opening, said damper being gravity actuated,

l a thermostatic coil having one end secured to the While I have described a specific constructional embodiment of my invention, it is obvious that l changes inl the parts, in the materials used for the parts, and in their relative mountings, may be made to suit the requirements for different boiler installations, without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. In a damper arrangement for a smoke stack, a casing having a base and a` cage upstanding therefrom, the top of said cage having an air inlet opening, a thermostat coil having one end secasing and the other end free and slidably supporting the damper, and an adjustable air inlet control for said opening comprising a housing on said cage overlying said cage inlet opening and having air inlet means, and adjustable draft operated auxiliary damper means pivotally mounted in said housing and controlling flow of air through said air inlet means, said cage having an upper wall, side and end walls, one end Wall being of substantially less height than the other end Wall and the side walls sloping'correspondingly to permit opening downward movement of the damper by gravity when -the casing is set in either horizontal or vertical position.

MICHAEL FISHER. 

